This invention relates generally to thermoelectric coolers and thermopile heat sensors fabricated on a micro-circuit.
The Peltier effect causes an absorption or liberation of heat when a current flows across the junction of two unlike metals. If the current flows in the same direction as the current at the hot junction in a thermoelectric circuit, heat is absorbed; if it flows in the same direction as the current at the cold junction of the thermoelectric circuit, heat is liberated.
Traditionally, the thermoelectric (T.E.) coolers are made with a p-type and an n-type conductor sandwhiched between two plates. With passage of direct current through the assembly, one of the plates would heat up while the other would cool down. The TE assembly is therefore of a hydrid type, requiring several assembly steps.
The fabrication of the thermopile heat sensors in which segments of alternately different metals are connected to form a series of thermocouple hot and cold junctions is well known. In order to measure the temperature, one junction which is exposed to heat receives the heat and a different junction which has one segment of metal in common with the heated junction is kept at a constant temperature. The temperature difference between the two junctions is measured by detecting a thermoelectromotive force generated by this temperature difference. This is known as the Seebeck effect. The plurality of the thermocouples in a thermopile helps to amplify the voltage difference for a more precise measurement.
Further advantages of the invention will become apparent as the following description proceeds.